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Surfactant structure effects in protein separations using nonionic microemulsions.
M Vasudevan1, K Tahan, J M Wiencek
1Department of Chemical and Biochemical Engineering, Rutgers University, P.O. Box 909, Piscataway, New Jersey 08855-0909.
Biotechnology and Bioengineering
|April 20, 1995
Summary
Sorbitan ester microemulsions effectively extract cytochrome c, showing high partition coefficients sensitive to ionic strength. The sorbitan group, not water content or chain length, is key to this protein extraction.
Area of Science:
- Biochemistry
- Physical Chemistry
- Chemical Engineering
Background:
- Nonionic surfactant microemulsions are used for protein extraction.
- Previous studies have shown varying success in protein partitioning.
- Understanding surfactant structure's effect on protein extraction is crucial.
Purpose of the Study:
- To investigate the impact of nonionic surfactant structure on cytochrome c extraction.
- To evaluate different microemulsion systems for protein partitioning.
- To determine the key factors influencing cytochrome c extraction efficiency.
Main Methods:
- Extraction of cytochrome c using various nonionic surfactant microemulsions.
- Testing linear alcohol ethoxylates, alkyl phenol ethoxylates, and sorbitan esters (Tweens and Spans).
- Analysis of protein partitioning, partition coefficients, and sensitivity to ionic strength, water content, and alkyl chain length.
Main Results:
- Hemoglobin dissociation and heme extraction were observed with Neodol 91-2.5, indicating false positives.
- Only sorbitan ester-based microemulsions successfully extracted significant amounts of cytochrome c.
- Achieved partition coefficients were an order of magnitude higher than previously reported for sorbitan systems.
- Partition coefficient was highly sensitive to ionic strength, decreasing significantly at 0.001 M.
- Protein partitioning was independent of water content, alkyl chain length, and polyethylene oxide molecular weight.
Conclusions:
- Sorbitan esters are effective nonionic surfactants for cytochrome c extraction.
- The sorbitan group plays a critical role in protein extraction, likely via weak electrostatic interactions.
- Ionic strength is a critical factor modulating the partition coefficient in these systems.
- Extraction efficiency is not dependent on surfactant hydrophobicity or ethylene oxide content.
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